This invention is concerned with improvements in or relating to orthodontic devices consisting of orthodontic brackets, particularly orthodontic brackets which comprise arch wire attitude controlling spring means as a permanent part thereof, and buccal tubes of convertible type, which may also comprise arch wire attitude controlling spring means as a permanent part thereof.
Orthodontic procedures almost always employ a plurality of orthodontic brackets that are attached to respective teeth, increasingly by cementing them to the teeth, although in some circumstances the bracket still may be attached to a metal band which embraces the tooth. Each bracket has a mesial distal extending slot therein, usually of rectangular cross section in a gingival occlusal plane, and the brackets are connected together using an arch wire, so called because it is preformed to an optimum arch shape corresponding to the desired conformation of the teeth at the conclusion of the procedure. Arch wires of progressively increasing stiffness and, depending on the type of tooth movement to be achieved, also of different cross sections, are used one at a time, the wire being retained in the slots by ligating means of some kind. Initially the brackets themselves were xe2x80x9cpassivexe2x80x9d, in that ligation of the wire to the bracket to obtain the necessary action between them was external to the bracket, at first consisting of a soft metal wire twisted around the bracket, while later an elastomeric hoop or loop increasingly was commonly used in place of the wire. In another line of development each bracket was made to be xe2x80x9cactivexe2x80x9d in that it comprised a permanent ligating spring member. Specific examples of such active brackets are disclosed and claimed in my U.S. Pat. Nos. 3,772,787; 4,248,588; 4,492,573; 4,698,017; 5,685,711; 5,711,666 and 5,906,486, the disclosures of which are incorporated herein by this reference. Brackets of this type currently are used in the Hanson SPEED System (Trade Mark) and have proven to be very successful.
The ends of the arch wire may be engaged in so-called buccal tubes, usually attached to the molars on respective sides of the patient""s mouth so as to anchor the arch wire firmly in place, and buccal tubes may also be employed on intermediate teeth in place of brackets whenever this is appropriate. In its simplest form a buccal tube is passive and consists of a short piece of tube attached to a base by which it is mounted on the tooth surface, the tube bore opening at least mesially so that the arch wire end must be inserted therein by moving it distally. This is not always convenient, and may not be possible when the buccal tube is on an intermediate tooth, and the solution is then to use a buccal tube of the so-called convertible type, with which one side of the tube bore can be opened when required for insertion of the wire therein or its removal. It is also possible to incorporate in the tube a wire engaging attitude controlling spring member that will urge the wire into contact with two of the slot walls, whereupon the tube is active as well as convertible.
It will be apparent from the foregoing brief general description of brackets and buccal tubes that there can be considerable overlap between both their function and appearance, with the result that it may be possible for a particular orthodontic device to be considered by some orthodontists as a bracket, while others will think of it as a buccal tube. In general, a device in which its body is noticeably bigger in gingival-occlusal dimension than mesiall-distally will usually be regarded by most practitioners as a bracket, while one in which the opposite is the case will be regarded as a buccal tube.
Inherently buccal tubes, especially those of the passive type, are smaller than most brackets and can have a smooth exterior. There is a constant endeavor to provide brackets that are as small and as smooth exteriorly as possible, for cosmetic reasons to please the patient, in order to reduce as much as possible any rough contact between the tongue, the brackets and the adjacent mouth tissue, with consequent discomfort, and for hygienic reasons to reduce the number of areas in which food and dental plaque can accumulate. The orthodontist is interested in addition to use both brackets and buccal tubes that while low in cost provide fast, precise and effective movement and attitude control of the teeth.
There is also increasing interest in the so-called lingual technique, in which the brackets are mounted on the lingual tooth surfaces, so that they and the arch wire are concealed from frontal view. Lingual procedures are more difficult to implement and a compromise is to use a lingual technique only for the upper arch, where the brackets and arch wire would otherwise be most visible, and a labial technique for the lower arch, where the brackets and arch wire are mostly hidden by the lower lip. Lingual and mixed lingual/labial procedures are of special interest to adult patients who are more concerned than children with appearance during the two to three year period required for a typical procedure. Small smooth brackets are needed particularly for the lingual location because of ready access by the tongue, and the natural tendency for the tongue to explore any foreign object in the mouth. Attempts simply to reduce the size of existing brackets are not generally successful, at least partly because changes in scale affects size parameters in different ratios, e.g. areas decrease in square ratio while volumes decrease in cube ratio, with the result that it becomes increasingly difficult, especially with the tiny spring members required, to find materials of the necessary properties. Examples of such small smooth exterior brackets suitable for lingual procedures are those described and claimed in my U.S. Pat. Nos. 4,698,017 and 5,685,711, issued respectively Oct. 6, 1987 and Nov. 11, 1997, referred to above.
Orthodontics is now a well established branch of dentistry, and the manufacture of orthodontic equipment is a mature industry. The ongoing requirement to provide appliances that are efficient, economical and easy to use increasingly has the added requirement to be as inexpensive as possible, especially if orthodontists are to be persuaded to make the changes in the procedures in which they were trained, and with which they are very familiar, that the adoption of new devices usually entails.
It is a principal object of the invention therefore to provide new orthodontic brackets, which preferably are of the type comprising a permanent attitude controlling metal spring that can engage an arch wire in the arch wire receiving slot, and buccal tubes of the so-called convertible type, which may also comprise a permanent attitude controlling metal spring.
It is another principal object to provide new brackets of small size and of an exterior shape that makes them specially suitable for use in lingual techniques, particularly in association with incisor or canine teeth.
It is a further object to provide such new brackets and convertible buccal tubes requiring a minimum number of parts and in which the cost of their fabrication is minimized.
In accordance with the invention there is provided an orthodontic device comprising:
a device body having labial, lingual, gingival, occlusal, mesial and distal surface portions, the body having therein a mesial-distal extending arch wire receiving slot having one side open to a device body surface portion to permit insertion of an arch wire into the slot, and
a slot closure member mounted by the device body so as to be movable about a pivot axis between a slot open position in which the open slot side is open, and a slot closed position in which the closure member closes the open slot side to retain an orthodontic arch wire in the slot;
wherein the slot closure member comprises:
a pivot portion mounted by the device body for the pivoting movement of the slot closure member about the pivot axis; and
a slot closure portion movable with the pivot portion and extending mesially-distally with respect to the device body;
and wherein the slot closure portion comprises:
a slot closure part that in the slot closed position closes the open side of the arch wire slot; and
at least one mesially-distally extending body engaging part that in the slot closed position of the slot closure member engages with an immediately adjacent surface portion of the device body with a rubbing, butting interference fit engagement between them providing a retaining force such that the slot closure member is retained thereby in the slot closed position, and such that movement of the slot closure member into the slot closed position requires flexing of the body engaging part in a direction away from the device body against the resilience of the material of the body engaging part.
Devices of the invention may constitute an orthodontic bracket or a convertible buccal tube.
Preferably there is provided in a recess within the device body a flat attitude controlling spring member having a fixed end portion fixed to the device body and a free end portion extending into the arch wire receiving slot for engagement in a mesially-distally extending plane with an arch wire in the slot, such engagement urging the arch wire toward the slot closure part.
Further in accordance with the invention there is provided an orthodontic bracket for application to the lingual surface of an incisor or canine tooth, which teeth are characterized in that their labial-lingual dimension increases progressively from the gingival to the occlusal, the bracket comprising:
a bracket body having labial, lingual, gingival, occlusal, mesial and distal surface portions, having therein a mesial-distal extending arch wire receiving slot with its lingual side open to the lingual surface portion to permit insertion of an arch wire into the slot, and having therein a recess opening to the lingual and occlusal surface portions;
the bracket body also comprising a slot closure member mounted by the bracket body in the recess so as to be movable about a pivot axis between a slot open position in which the open slot side is open, and a slot closed position in which it closes the open slot side to retain an orthodontic arch wire therein, the slot closure member also having labial, lingual, gingival, occlusal, mesial and distal surface portions;
wherein in the slot closed position the occlusal surface portion of the slot closure member is flush with the occlusal surface portion of the bracket body to thereby provide a combined occlusal surface which is unobstructed; and
wherein the gingival-occlusal dimension of the bracket body decreases progressively from the lingual to the labial, the decrease corresponding to the average increase from the occlusal to the gingival of an incisor or canine tooth, so that when the bracket is attached to the lingual surface of an incisor or canine tooth the unobstructed combined occlusal surface provides a mesial-distal, labial-lingual extending bite plane surface which the tooth edge at the junction of the occlusal and labial surface portions of an opposed incisor or canine tooth can engage during biting action to oppose overbite.